许多研究强调了时钟基因在糖尿病疾病和胰腺β细胞功能中的作用。然而,有节奏的长链非编码RNA是否参与这一过程尚不清楚.在这里,我们发现,由核心时钟转录因子BMAL1驱动的富含胰岛的节律性长非编码RNALncCplx2在体外和体内调节胰腺β细胞功能中起着至关重要的作用。机械上,LncCplx2招募EZH2,这是多聚抑制复合物2(PRC2)的核心亚基,目标基因的启动子,从而沉默昼夜节律基因表达,这导致胰岛素分泌和细胞周期基因的相移和振幅变化。始终如一,LncCplx2KO小鼠表现出糖尿病表型,如高血糖和糖耐量受损。值得注意的是,LncCplx2缺乏对昼夜节律行为有显著影响,包括延长的持续时间,运动活动减少,降低代谢率。总的来说,我们的研究结果表明LncCplx2是昼夜节律系统中一个意想不到的转录调节因子,并为昼夜节律和葡萄糖稳态的协调提供了一个更完整的机制.
OBJECTIVE: Numerous studies have highlighted the role of clock genes in diabetes disease and pancreatic β cell functions. However, whether rhythmic long non-coding RNAs involve in this process is unknown.
METHODS: RNA-seq and 3\' rapid amplification of cDNA ends (RACE)-PCR were used to identify the rat LncCplx2 in pancreatic β cells. The subcellular analysis with qRT-PCR and RNA-Scope were used to assess the localization of LncCplx2. The effects of LncCplx2 overexpression or knockout (KO) on the regulation of pancreatic β cell functions were assessed in vitro and in vivo. RNA-seq, immunoblotting (IB), Immunoprecipitation (IP), RNA pull-down, and chromatin immunoprecipitation (ChIP)-PCR assays were employed to explore the regulatory mechanisms through LncRNA-protein interaction. Metabolism cage was used to measure the circadian behaviors.
RESULTS: We first demonstrate that LncCplx2 is a conserved nuclear long non-coding RNA and enriched in pancreatic islets, which is driven by core clock transcription factor BMAL1. LncCplx2 is downregulated in the diabetic islets and repressed by high glucose, which regulates the insulin secretion in vitro and ex vivo. Furthermore, LncCplx2 KO mice exhibit diabetic phenotypes, such as high blood glucose and impaired glucose tolerance. Notably, LncCplx2 deficiency has significant effects on circadian behavior, including prolonged period duration, decreased locomotor activity, and reduced metabolic rates. Mechanistically, LncCplx2 recruits EZH2, a core subunit of polycomb repression complex 2 (PRC2), to the promoter of target genes, thereby silencing circadian gene expression, which leads to phase shifts and amplitude changes in insulin secretion and cell cycle genes.
CONCLUSIONS: Our results propose LncCplx2 as an unanticipated transcriptional regulator in a circadian system and suggest a more integral mechanism for the coordination of circadian rhythms and glucose homeostasis.